Field of the Invention
The present invention generally relates to treating sleep disorders, and more specifically relates to systems, devices and methods for treating patients suffering from obstructive sleep apnea.
Description of the Related Art
Obstructive sleep apnea (OSA) is caused by a blockage of the airway, which usually occurs when the soft tissue in the throat collapses and closes during sleep. The blockage can occur in a portion of the pharyngeal lumen and may include obstructions formed by the collapse of the tongue against the posterior wall of the pharynx, the collapse of the lateral pharyngeal walls, and the combined collapse of the tongue with impingement of the soft palate, particularly the posterior portion of the soft palate including the uvula. During each apnea event, the brain briefly arouses the sufferer in order to initiate the resumption of breathing. This type of sleep, however, is extremely fragmented and of poor quality.
According to the National Institutes of Health, OSA affects more than twelve million Americans. When left untreated, OSA may result in high blood pressure, cardiovascular disease, weight gain, impotency, headaches, memory problems, job impairment, and/or motor vehicle crashes. Despite the seriousness of OSA, a general lack of awareness among the public and healthcare professionals results in the vast majority of OSA sufferers remaining undiagnosed and untreated.
There have been a number of efforts directed to treating OSA. For example, devices for electrically stimulating the soft palate to treat snoring and obstructive sleep apnea are disclosed in U.S. Pat. Nos. 5,284,161 and 5,792,067. Use of these devices have had mixed results because they require patient adherence to a strict regimen of use, subject the patient to discomfort during sleep, and result in repeated arousal of the patient.
Another treatment, commonly referred to as continuous positive airway pressure (CPAP), delivers air into a patient's airway through a specially designed nasal mask or pillow. The flow of air creates positive pressure when the patient inhales to keep the airway open. CPAP is considered by many to be an effective non-surgical treatment for the alleviation of snoring and obstructive sleep apnea, however, patients complain about discomfort caused by the mask and hoses, including bloating, nasal drying, and dry eyes. As a result, patient compliance for CPAP is only about 40%.
Surgical treatments have also been used to treat OSA. One such treatment is referred to as uvulopalatopharyngoplasty, which involves removing about 2 cm of the trailing edge of the soft palate to reduce the soft palate's ability to flutter between the tongue and the pharyngeal wall. Another procedure uses a surgical laser to create scar tissue on the surface of the soft palate, which reduces the flexibility of the soft palate for reducing snoring and/or closing of the air passage. Yet another procedure, commonly referred to as cautery-assisted palatal stiffening operation (CAPSO), is an office-based procedure performed under local anesthesia whereby a midline strip of soft palate mucosa is removed, and the wound is allowed to heal for stiffening the palate.
Surgical procedures such as those mentioned above continue to have problems. Specifically, the area of tissue that is surgically treated (i.e., removal of palatal tissue or scarring of palatal tissue) is often larger than is necessary to treat the patient's condition. In addition, the above-mentioned surgical procedures are often painful with extended, uncomfortable healing periods. For example, scar tissue on the soft palate may present a continuing irritant to the patient. Furthermore, the above procedures are not reversible in the event of adverse side effects.
Another surgical procedure for treating OSA uses several braided PET cylinders that are implanted in tissue to make the tissues of the tongue or uvula more rigid and less prone to deflection. The Pillar™ Palatal Implant System sold by Restore Medical of St. Paul, Minn. consists of cylindrical-shaped elements of braided polyester filaments that are implanted in the soft palate for reducing the incidence of airway obstructions in patients suffering from mild to moderate OSA. Use of the Pillar device may result in adverse side effects, including extrusion of the cylindrical-shaped elements, infection, and patient discomfort.
Another implant system, sold under the trademark REPOSE™ by InfluENT of Concord, N.H., uses a titanium bone screw that is inserted into the posterior aspect of the mandible at the floor of the mouth. A loop of suture is passed through the tongue base and attached to the mandibular bone screw. The Repose™ procedure achieves a suspension or hammock of the tongue base making it less likely for the base of the tongue to prolapse during sleep. Due to the high activity of the tongue during wakefulness, however, the suture component of this device may act as a “cheese cutter” to the tongue, causing device failure and requiring subsequent removal.
Another effort for treating OSA involves creating an auxiliary airway for bypassing the clogged portion of the main airway. In one embodiment of commonly assigned U.S. patent application Ser. No. 12/182,402, filed Jul. 30, 2008, the disclosure of which is hereby incorporated by reference herein, an auxiliary airway is formed by implanting an elongated conduit beneath a pharyngeal wall of the pharynx. The elongated conduit has a proximal end in communication with a first region of the pharynx, a distal end in communication with a second region of the pharynx, and an intermediate section extending beneath the pharyngeal wall for bypassing an oropharynx region of the pharynx.
Magnets have also been used for treating OSA. For example, in one embodiment of commonly assigned U.S. patent application Ser. No. 12/183,955, filed Jul. 31, 2008, the disclosure of which is hereby incorporated by reference herein, a magnetic implant includes a bone anchor, a first magnet coupled to the bone anchor, a tongue anchor, a second magnet coupled to the tongue anchor, and a support for aligning the first and second magnets so that a repelling force is generated between the magnets for urging the second magnet away from the first magnet and toward the bone anchor. The support maintains the first magnet at a fixed distance from the bone anchor, aligns the first magnet with the second magnet, and guides movement of the first and second magnets. The magnetic implant disclosed in one or more embodiments of the '955 application does not have a hard stop so as to avoid the “cheese-cutter” effect observed when using implants having a hard stop.
In spite of the above advances, there remains a need for additional systems, devices and methods for treating OSA through minimally invasive approaches that provide long-term efficacious results, that encourage patient compliance, and that minimize patient discomfort.